The present invention relates to empty and load brake devices for railway vehicles and is particularly concerned with a load dependent braking pressure regulating device for railway vehicles.
Various types of empty and load brake devices have been developed in the former USSR, Germany, Japan and the USA. These known devices can adjust the brake cylinder air pressure in two steps, multi-steps or in a stepless manner. Some of them have been once used in China but failed very soon due to their incapability of meeting the actual conditions in China and hence, have been ruled out of the Chinese market; and some of them cannot match the brake control valves to which two braking pressures are directly applied and hence are difficult to be applied and disseminated in China. Therefore, manually manipulated two-step empty-load switching devices have been widely using in China. In use, such switching devices are sometimes wrongly switched or forgotten to be operated, leading to railway wheel slide. With the development of railway transportation and freight car manufacturing technology, the two-step empty and load brake device often than not results in flat wheels of the freight cars due to increased pay load, decreased empty weight and increased load and empty ratio. Under the condition of empty car or partially loaded car, the car brake rate is too high. When the wheel/rail adhesion coefficient drops due to weather and environment changes, the tread of wheels tends to be damaged. With the development of heavy haul train operation and increased train speed, accidents of flat wheels are increasingly happened, thus threatening operation safety and increasing the maintenance and operation cost.
Accordingly, it is an object of the present invention to provide a load dependent braking pressure regulating device for railway vehicles which can match the performance of the control valve, to which two pressures are directly applied, such as 120 valves, GK valves and ABDW valves. The device according to the present invention can replace the existing manually operated devices for switching between empty and load and the safety valves; not only ensures sufficient braking force under different loads or no load, but also effectively presents flat wheel accidents resulted from excessive brake force which is greater than that the wheel/rail adhesion can handle, whereby the brake and release performance of the train brake system is improved, the demands by heavy haul trains and speed raising are met and the safety of train operation and the quality of transportation are, enhanced.
To achieve the above object of the present invention, there is provide a load dependent braking pressure regulating device for railway vehicles comprising an auxiliary reservoir for storing pressurized air from a train pipe; a brake cylinder; and a control valve operated by means of the pressure difference between the train pipe and the auxiliary reservoir in such a manner that the pressurized air from the auxiliary reservoir enters the brake cylinder through the control valve upon braking and that the pressurized air from the brake cylinder is discharged to the atmosphere through the control valve when the brake cylinder is released, characterized in that a regulating valve, a sensor valve, a triggering board transmission mechanism and a stop disc are provided between the control valve and the brake cylinder, a triggering head provided at the lower end of the stop disc being directly opposite the center of a triggering board of the triggering transmission mechanism, and the sensor valve being connected through pipes with the control valve, the regulating valve, the brake cylinder and the pressure reduction reservoir respectively.
The load dependent braking pressure regulating device according to the present invention has the following advantageous effects over the conventional technology:
1) The device according to the present invention can adjust the brake cylinder air pressure steplessly and automatically in accordance with the car load and can replace the existing manually operated two-step empty and load switching mechanism and its safety valve so that the control between empty and load can be automatized, and the consumption of braking air and the time for recharging braking air can be reduced.
2) The device according to the present invention can reduce the brake cylinder air pressure and brake rate under empty and partially loaded conditions, keep an even brake rate under different loads, which is always greater than the brake rate of a fully loaded car, and to ascertain a safe brake distance;
3) With the device according to the present invention, the brake force in empty or partially loaded condition will be kept smaller than the wheel/rail adhesion so as to prevent accidents of flat wheels, reduce abnormal wheel wear and car maintenance work, raise the car utilization rate and transportation efficiency, reduce the damages to rail connections, bridges and car bearings due to flat wheels, thus improving the safety of train operation;
4) Because of the uniform brake rate under different car loads of one train, the longitudinal impact between differently loaded cars in one train at brake application will be reduced. Because of this device matching neatly with the two-pressure directly-controlled brake valve, the train pipe effective pressure reduction under different loads is more or less the same, the release of each car in a mixed consist train is more uniform, the longitudinal release impact between cars can be effectively reduced when the brake system is operated or released. The reduction of longitudinal brake and release impact between cars is conducive to improvement of freight transportation quality and safety;
5) The device is well located, accurate in weight measurement, less influenced by side-roll, vibration, tilting on curve and unbalanced loading.
6) The device matches neatly with the two-pressure directly-controlled brake valve. The brake and release performance under different loads tends to be the same, reduces the release time of empty cars and partially loaded cars. It is conducive to operate long and heavy haul trains and increase the freight train operation speed.
7) The device is simple in structure and reliable in operation, and needs less maintenance. Since all moving parts of the sensor valve and the regulating valve are sealed with Y-shaped rubber seals with no wearable parts, the maintenance period is long.
8) The device makes it possible to have no mechanical connection such as pipes between the car body and the truck. So during maintenance, the car body can be raised and separated from the truck without dismantling any parts.
9) The device is adaptable to various kinds of cars, very strong in adaptability;
10) The application and dissemination of the device will bring up significant economical and social benefits to the railway industry.